Many electronic devices include or are connected to amplification devices that amplify input signals and generate amplified output signals. As is well known in the art, these amplification devices may increase or decrease a signal level of the input signal in accordance with a gain. To place the input signal within an operating range of the amplification device, a bias signal is applied to the input signal. Generally, the bias signal is a DC signal that shifts the input signal into the operating range of the amplification device. A quiescent operating level of the amplified output signal is thus determined in accordance with the bias signal level of the bias signal.
Ideally, the quiescent operating level of the input signal remains consistent and does not change. Furthermore, under ideal circumstances, the quiescent operating level is consistent so that amplification devices in a manufactured population of amplification devices have the same quiescent operating level. However, in practice, this is not generally the case. First, the quiescent operating level of the amplification device can drift. For example, transistors in the amplification device may heat up resulting in change to the quiescent operating level during operation of the amplification device. Second, process variations in the manufacturing of the amplification device can result in variations in the quiescent operating level. The drift and manufacturing variations lead to various inefficiencies such as loss of linearity, noise, a decrease in the Adjacent Channel Power Ratio (ACPR), a decrease in Power Added Efficiency (PAE), and/or the like.
Therefore, RF amplification devices and methods are needed that reduce, compensate for, or eliminate inefficiencies resulting from drifts and manufacturing variations in the quiescent operating level.